1) write specific procedure with details (as though the teachers don't know anything)
2) clear
3) systematic
4) concise
say:
-label white tile
-add a drop of iodine each onto A,B and C
-equal amounts of substrate and enzyme
-use thermometer to measure 37 degrees (use word incubate)
must test for starch at the beginning before putting into water bath
-to show difference in colour
-as a control
-comparison between beginning and end
use the words"remained"/ "turned" for iodine test
-it's the mixture that turned colour, not the iodine itself
starch "present" or "absent"
-use the word "hydrolysed" for starch
Tube
Contents
Observations
Conclusions
0min
10min
X
B + A
turned blue- black
remained brown
Starch is absent. Starch is hydrolysed
Y
C + A
turned blue-black
turned blue-black
Starch is present
Possible precautions:
-ensure tile is dry
-no parallax error
-ensure that you mention precautions in the procedure
-explain precautions
REDUCING SUGARS TEST
-add equal amount of benedict's solution to unknown
-mix
-submerge in boiling water bath for 5 min/ when see coloured precipitate (from green to yellow to orange to brick-red) formed
-if remains blue, reducing sugar is absent
ETHANOL EMULSION TEST
-test tube must be dry
-one or two drops of oil
-or ground solid
-add ethanol
-water
-shake
-should see white suspension
-exothermic reaction (should become warm)
*need to know diffusion, osmosis, digestion, food tests, carbo lipid protein
- salivary enzymes(amylase) work best in pH 7
- pepsin(stomach enzymes) work best in pH 4
- intestinal enzymes work best in alkaline pH
proteins coagulate/change structure is different from digestion
2) clear
3) systematic
4) concise
say:
-label white tile
-add a drop of iodine each onto A,B and C
-equal amounts of substrate and enzyme
-use thermometer to measure 37 degrees (use word incubate)
- must test for starch at the beginning before putting into water bath
-to show difference in colour-as a control
-comparison between beginning and end
- use the words"remained"/ "turned" for iodine test
-it's the mixture that turned colour, not the iodine itself- starch "present" or "absent"
-use the word "hydrolysed" for starch-ensure tile is dry
-no parallax error
-ensure that you mention precautions in the procedure
-explain precautions
REDUCING SUGARS TEST
-add equal amount of benedict's solution to unknown
-mix
-submerge in boiling water bath for 5 min/ when see coloured precipitate (from green to yellow to orange to brick-red) formed
-if remains blue, reducing sugar is absent
ETHANOL EMULSION TEST
-test tube must be dry
-one or two drops of oil
-or ground solid
-add ethanol
-water
-shake
-should see white suspension
-exothermic reaction (should become warm)
*need to know diffusion, osmosis, digestion, food tests, carbo lipid protein
- salivary enzymes(amylase) work best in pH 7
- pepsin(stomach enzymes) work best in pH 4
- intestinal enzymes work best in alkaline pH
- proteins coagulate/change structure is different from digestion
-acids make protein coagulate